Image Measuring Apparatus and Method, and Image Measuring System for Glomerular Filtration Rate

1. An abdominal CT image measuring apparatus, comprising: an interface unit, for obtaining two-phase or multi-phase scan images of a part under test, wherein said scan images comprise plain scan images series and enhanced scan image series; a part recognizing unit, for outputting a correspondence between the scan images in two different phases obtained by the interface unit by a registration algorithm, for comparing CT values of corresponding points on the scan images in two different phases, and for determining the corresponding points on the scan images in two different phases belong to the part under test when a difference between the CT values of said corresponding points is greater than or equal to a predetermined threshold; and a characteristic data computing unit, for extracting the CT values of said points representing the part under test, and computing required characteristic data of the part under test based on the difference between the CT values of the points representing a same position of the part under test on the images in different phases.

2. The abdominal CT image measuring apparatus according to claim 1 , wherein said points belonging to the part under test together constitute said part under test and are displayed on the abdominal CT images.

3. The abdominal CT image measuring apparatus according to claim 1 , wherein said plain scan images are abdominal CT plain scan images, said enhanced scan images comprise abdominal CT arterial phase images and abdominal CT delayed phase images, and said part under test includes kidneys and abdominal aorta; and said part recognizing unit is used for recognizing the points representing the kidneys and the abdominal aorta on the plain scan images, the arterial phase images and the delayed phase images, and for segmenting a kidney region and an abdominal aorta region.

4. The abdominal CT image measuring apparatus according to claim 3 , wherein said characteristic data computing unit comprises: a kidney volume determining subunit, for extracting the volume and the number of data voxels contained in each of said segmented kidney regions and computing each kidney volume; an added average CT value determining subunit, for extracting the CT values corresponding to the points in said segmented kidney regions, computing the added average CT values of the kidney regions in the arterial phase and the delayed phase relative to the plain scan images, extracting the CT values corresponding to the points in said segmented abdominal aorta region, and computing the added average CT values of the abdominal aorta region in the arterial phase and the delayed phase relative to the plain scan images; a curve determining subunit, for obtaining a curve of the average CT value of the abdominal aorta region varying with time by a regression analysis; and a glomerular filtration rate determining subunit, for computing the glomerular filtration rates based on the above parameters.

5. The abdominal CT image measuring apparatus according to claim 3 , wherein said part recognizing unit comprises: a selecting subunit, for selecting a point at the abdominal aorta on the plain scan images as a seed point; and a growing subunit, for starting a region growing from said seed point and obtaining a region of which the CT value is greater than a preset growth threshold, wherein said region is the segmented abdominal aorta on the plain scan images.

6. The abdominal CT image measuring apparatus according to claim 5 , wherein said part recognizing unit further comprises: an abdominal aorta region determining subunit, for obtaining, on the arterial phase images and the delayed phase images, a region corresponding to the segmented abdominal aorta on the plain scan images, based on said segmented abdominal aorta on the plain scan images and the correspondence between the plain scan images and the arterial phase images as well as the correspondence between the plain scan images and the delayed phase images output by the registration algorithm.

7. The abdominal CT image measuring apparatus according to claim 4 , wherein said characteristic data computing unit further comprises: a correcting subunit, for correcting the computed glomerular filtration rates.

8. The abdominal CT image measuring apparatus according to claim 4 , wherein said part recognizing unit further comprises a right and left kidney distinguishing subunit, for determining the right and left kidneys in said kidney regions; and said glomerular filtration rate determining subunit is used for computing the glomerular filtration rates of the right and left kidneys respectively.

9. A method for measuring abdominal CT images, comprising: an obtaining step, for obtaining two-phase or multi-phase scan images of a part under test, wherein said scan images comprise plain scan image series and enhanced scan image series; a recognizing step, for outputting a correspondence between the scan images in two different phases by a registration algorithm, for comparing CT values of corresponding points on the scan images in the two different phases, and for determining the corresponding points on the scan images in the two different phases belong to the part under test when a difference between the CT values of said points is greater than or equal to a predetermined threshold; and a computing step, for extracting the CT values of said points representing the part under test, and computing required characteristic data of the part under test based on the difference between the CT values of the points representing a same position of the part under test on the scan images in different phases.

10. The method for measuring abdominal CT images according to claim 9 , wherein said points belonging to the part under test together constitute said part under test and are displayed on the abdominal CT images.

11. The method for measuring abdominal CT images according to claim 9 , wherein said scan images comprises abdominal CT plain scan images, arterial phase images and delayed phase images; and points representing kidney and abdominal aorta on the plain scan images, the arterial phase images and the delayed phase images are recognized, and kidney regions and an abdominal aorta region are segmented.

12. The method for measuring abdominal CT images according to claim 11 , wherein said computing step comprises: extracting the volume and the number of data voxels contained in each of said segmented kidney regions, and computing each kidney volume; extracting the CT values corresponding to the points in said segmented kidney regions, and computing the added average CT values of the kidney regions in the arterial phase and delayed phase relative to the plain scan images; extracting the CT values corresponding to the points in said segmented abdominal aorta region, and computing the added average CT values of the abdominal aorta region in the arterial phase and the delayed phase relative to the plain scan images; obtaining a curve of the average CT value of the abdominal aorta region varying with time by a regression analysis; and computing the glomerular filtration rates based on the above parameters.

13. The method for measuring abdominal CT images according to claim 11 , wherein the abdominal aorta is segmented on the plain scan images by the following steps: selecting a point at the abdominal aorta on the plain scan images as a seed point; and starting a region growing from said seed point and obtaining a region of which the CT value is greater than the preset growth threshold, wherein said region is the segmented abdominal aorta on the plain scan images.

14. The method for measuring abdominal CT images according to claim 13 , wherein the abdominal aorta is segmented from the arterial phase images and the delayed phase images by the following step: obtaining, on the arterial phase images and the delayed phase images, a region corresponding to the abdominal aorta segmented on the plain scan images, based on said segmented abdominal aorta on the plain scan images and the correspondence between the plain scan images and the arterial phase images as well as the correspondence between the plain scan images and the delayed phase images output by the registration algorithm.

15. The method for measuring abdominal CT images according to claim 12 , further comprising: correcting the computed glomerular filtration rates.

16. The method for measuring abdominal CT images according to claim 12 , wherein said recognizing step further comprises determining the right and left kidneys from said kidney regions; and said computing step further comprises computing the glomerular filtration rates of the right and left kidneys respectively.

17. An image measuring system for glomerular filtration rate, comprising an image scanning and reconstructing subsystem and an image-processing subsystem, wherein said image scanning and reconstructing subsystem is used for scanning and outputting plain scan images, arterial phase images and delayed phase images; and said image-processing subsystem is used for image processing and characteristic data measuring, and comprises: a segmenting unit, for segmenting kidney and abdominal aorta from the plain scan images, the arterial phase images and the delayed phase images respectively; a parameter determining unit, for obtaining the volume and the number of data voxels contained in the segmented kidney regions and computing each kidney volume, obtaining the average CT values of said kidney regions and the segmented abdominal aorta region, computing the added average CT values of the kidneys and the abdominal aorta in the arterial phase and the delayed phase, and obtaining a curve of the average CT value of the abdominal aorta varying with time by a regression analysis; a glomerular filtration rate determining unit, for computing the glomerular filtration rates based on the above parameters; and a display unit, for displaying said glomerular filtration rates.

18. The image measuring system for glomerular filtration rate according to claim 17 , wherein the information displayed on said display unit further comprises: the segmented kidney regions and abdominal aorta region, or the curve of the average CT value of said abdominal aorta varying with time.